1. Field of Invention
The present invention relates to a projector.
2. Description of Related Art
Projectors have been developed with an aim to enhance their contrasts. Some projectors are provided with a diaphragm in a projection lens. For example, a related art projector is disclosed in Japanese Unexamined Patent Application Publication No. 5-303085. According to the document, a projection display device includes a lighting apparatus, a device to incorporate image data into light beams from the lighting apparatus by modulating the light beams, and a projection optical system that projects the modulated light beams on a screen. The lighting apparatus focuses light emerged from a light source lamp with a focusing device, forms at least one secondary light source, and illuminates the device to incorporate image data with light beams emitted from the secondary light source. The device to incorporate image data is a light bulb using a liquid crystal composite element that modulates incident light beams depending on the degree of diffusion. An image of the secondary light source is formed inside or in the vicinity of the projection optical system, where a projection diaphragm, that is perpendicular to the optical axis of the projection optical system, is provided. The shape of an opening of the projection diaphragm is nearly the same as the outline of the image of the secondary light source formed within an area including the projection diaphragm.